The invention relates to a subrack with two side walls, with at least one cover plate as well as at least one bottom plate, wherein the cover plate and the bottom plate are fixed between the side walls, and the cover plate as well as the bottom plate display a bent section projecting at a right angle.
Subracks, as they serve the reception of insertable subassemblies fitted with electrical and electronic components, have long been known in the industry for a long time.
In the simplest implementation such a subrack consists of two side walls and four module rails with their facial surfaces on both sides screwed to the inner surfaces of the stampedxe2x80x94out side walls, the latter being of aluminum. A cover plate and a bottom plate as well as a back wall can allow the subrack to be a closed housing, from whose open front side the subassemblies are pushed onto the fitted guide rails. The subassemblies exhibit partial front plates that rest on the two forward module rails and are screwed in above and below. Devices for insertion and withdrawal, which connect to the module rails, complete the subrack.
The module rails required for the subrackxe2x80x94in order to satisfy all the requirements for fastening the partial front plate and the guide railsxe2x80x94exhibit a more or less elaborately formed profile; therefore they consist of extruded aluminum. Complicated tools are required for production of these module rails, whose manufacture is thus expensive. Attempts to produce the module rails through multiple bendings of strips of sheet steel have failed up to now because the awkward large bending radii do not allow the required sharp-edged transitions of neighboring surfaces. This is where the invention comes into effect.
To be sure, a housing is known for receiving of insertable subassemblies (U.S. Pat. No. 4,277,120) that exhibits two side walls, a cover plate and a bottom plate, wherein the cover plate carries a bent section projecting at a right angle that serves the fixing of a lower U-rail for insertion of label strips.
With another known subrack, provision is made for the connection of module rails to the side walls, a cover plate and a bottom plate, which in each case are fabricated of two U-rails of different width that engage one another. Serving the connecting of the latter are sheet metal carriers projecting at the inner rail, the carriers engaging in slots in the bracing of the outer, wider U-rail (DE-OS 195 23 964).
A known cost-effectively producible subrack possesses two side walls that can be stuck together with the cover part and the bottom part. For this, the sides carry meandering punched-out edges, whose fingers engage in trapezoidal stamped-out bulges that are provided at inwardly projecting bent sections of the cover and bottom (DE 295 02 404). Front side and backside transverse bars are formed through multiple bendings of the bottom part and the cover part.
The object of the invention consists in the concept of an especially cost-effectively producible subrack.
Proceeding as a starting point from a known subrack as described in the introduction, the object is achieved through the following constructive measures, namely: an angled strip is placed, in each case, on the cover plate or, as the case may be, on the bottom plate parallel to the bent section [of the top plate or the bottom plate]. The angled strip possesses a wide leg and a narrow leg bent at a right angle, the narrow leg carrying a series of threaded holes. The bent section is situated with its longitudinal edge against the inside of the wide leg; the narrow leg is situated with its outer edge against the outside of the cover plate or the bottom plate, as the case may be. The bent section exhibits a series of holes that are aligned with the threaded holes, and along the longitudinal edge of the bent section and the outer edge provision is made for connecting means.
Provision is made for several parallel rows of rectangular and circular holes and openings for receiving the fastening means of insertable guide rails.
With the proposed subrack there are no longer any separate module rails, rather these are integrated components of the cover plate and the bottom plate. The production of the designed angled strip intended for mounting on the front edges or the rear edges of the cover plate or the bottom plate can be produced with no problem in the context of sheet-metal processing through shearing, bending and hole punching. The same is true for the associated formation of the bent section of the cover plate and the bottom plate. The abutting edge between the bent section of the cover plate or the bottom plate and the wide leg of the angled strip is sharp edged. This allows a flawless mounting of the partial front plate of the inserted subassemblies. In contrast to extruded aluminum profiles for separate module rails, there is a crucial simplification and a lowering of cost of the essential parts of a subrack.
Appropriately, the cover plate, the bottom plate as well as the angled strip consist of equal-thickness corrosion-protected sheet steel. This serves the simplification of production.
At least some of the holes of the bent section are designed as alignment holes. Engaging these are positioning pins projecting from the rear side of the partial front plate.
Advantageously, the wide leg of the angled strip forms a prominent projection in which provision is made for rectangular openings in a row. This projection (usually described as a xe2x80x9croofxe2x80x9d) serves along with the rectangular openings as an abutment for the insertion and withdrawal devices on the subassemblies.
According to an important feature of the development of the invention, protruding along the outer edge of the narrow leg as a connecting means is a first row of tines that engage a first row of receptacles in the cover plate or the bottom plate.
In addition, for increasing the firmness of the connection of the angled strip to the cover plate or the bottom plate, as a connecting means along the bent section of the cover plate or the bottom plate, a second row of tines protrudes, the latter engaging a second row of receptacles in the wide leg of the angled strip.
Advantageously, the row of tines is arranged in each case slightly displaced with respect to the row of receptacles, so that a good, reliable clamping connection is achieved in the joining of the parts.
Through a pressing down by means of a tool of the upper side of tines situated in the receptacles as in a riveting process, the firmness of the connection can be increased still more.
Instead of the connection by means of dovetails engaging the receptacles, provisions can be made for only an adhesive. This makes unnecessary the production of tines or receptacles by a stamping of the components to be connected, so that costs can be additionally reduced. Any other known fastening method can be used for connection along the outer edge of the narrow leg and the bent section of the cover plate and the bottom plate.
Appropriately, the cover plate and the bottom plate exhibit at their side edges brackets protruding at a right angle, the brackets being provided with mounting holes, the latter aligned with threaded holes on the longitudinal edges of the side walls. Through this, the fastening of the cover plate and the bottom plate to the sides of the subrack is made possible in a simple manner.
Another considerable cost saving can be achieved if the cover plate and the bottom plate are designed to be identical.
A gap can be provided between the bent section and the narrow leg, whereby a closed channel of rectangular cross-section can be formed between the cover plate or the bottom plate and the angled strip. This considerably increases the rigidity of the front edges of the cover plate and the bottom plate that are provided with the angled strip. Their rear edges are provided with an additional bent section.
According to another feature of relevance to the invention, the cover part and the bottom part exhibit at their rear edges another angled strip as well as an extension that corresponds to that of the front face side.
It is particularly advantageous if the cover plate and the bottom plate are produced integrally with the cover part and the bottom part, respectively, and if the cover part as well as the bottom part exhibit at their rear edge another angled strip as well as an extension that corresponds to that of the front face side.